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Date: Mon, 24 Sep 2007 12:04:07 +0300 From: "Ilpo Järvinen" <ilpo.jarvinen@...sinki.fi> To: David Miller <davem@...emloft.net> Cc: netdev@...r.kernel.org Subject: [RFC PATCH 2/3] [TCP]: Reordered ACK's (old) SACKs not included to discarded MIB In case of ACK reordering, the SACK block might be valid in it's time but is already obsoleted since we've received another kind of confirmation about arrival of the segments through snd_una advancement of an earlier packet. I didn't bother to build distinguishing of valid and invalid SACK blocks but simply made reordered SACK blocks that are too old always not counted regardless of their "real" validity which could be determined by using the ack field of the reordered packet (won't be significant IMHO). DSACKs can very well be considered useful even in this situation, so won't do any of this for them. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...sinki.fi> --- net/ipv4/tcp_input.c | 7 ++++++- 1 files changed, 6 insertions(+), 1 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 532288b..ae06b94 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1250,8 +1250,13 @@ tcp_sacktag_write_queue(struct sock *sk, struct sk_buff *ack_skb, u32 prior_snd_ NET_INC_STATS_BH(LINUX_MIB_TCPDSACKIGNOREDNOUNDO); else NET_INC_STATS_BH(LINUX_MIB_TCPDSACKIGNOREDOLD); - } else + } else { + /* Don't count olds caused by ACK reordering */ + if ((TCP_SKB_CB(ack_skb)->ack_seq != tp->snd_una) && + !after(end_seq, tp->snd_una)) + continue; NET_INC_STATS_BH(LINUX_MIB_TCPSACKDISCARD); + } continue; } -- 1.5.0.6 - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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